Will 13" corvette brakes (C4 HD or C5) fit under stock 1989 IROC 16" wheels? What parts would I need and where can I get them? I can have a set of stock rotors machined into a hub if necessary, but I don't have access to any equipment necessary to make mounting brackets.

I've been considering Ed Miller's 12" kit, but would really like 13" if possible. I hear that Baer's 13" will fit the IROC wheels (unconfirmed), but If I can get the same setup cheaper, why spend the extra $$. I want as much braking as I can get, as the stock brakes are definately not enough.

I've done a bunch of searches (hard as search cannot recognize terms C4 or C5) and read more posts than I can count, but I think I'm more confused. Can someone put this is simple terms for me?

Thanks

I have the C5s now. It's the caliper that won't clear. Ed is still workin on trying to fit a 13" HD rotor and a earlier caliper so that it'll fit in the 16's. You could search C4 and C5 like this: C4* and C5* (where * is a wildcard, but i dont think it'll find anything else but C4 and C5, it didn't for me).

Hi guys. I still haven't fit up the Iroc wheel with the 13" HDs yet, I don't have the "test" rotor anymore, but my new HD rotors will be here early next week and I'll do the fit ups then, both on the 16" Iroc and the 16" RS wheels. I'll post pics of it all, but I am 95% sure they'll fit no problem.

Ed

Thanks for the info.

Ed. Will you be offering a kit using the 13" rotor?

I will have my new rotors in this week so I can work more on it. I will be fitting up a 16" Iroc and RS wheels and will post pics.

89Iroc-ZL98,

Sent you a PM.

Ed

Rotors came in today, pics later.

Ed

OK, here's the verdict: Yes to both the RS wheel and the Iroc wheel. Funny thing while I was fitting these up. My 1/8" spacer was too thick for some reason. I didn't fit the wheels up with the same hubs, that's the only change. I ended up using 5- 1/16" washers on the studs to space it out right. The "old" set of hubs are on Lock's car now, and they weren't GM hubs. The set I used today were old GM parts, so there has to be a difference in aftermarket and GM heights. I still have to make the hub from the 1LE rotor so that will be different too.

Here' s pics starting with the RS wheel:

Back view:

Iroc wheel:

Back view:

Wanna know what else is neat? I haven't pulled the front wheel off the Iroc since the 1LE upgrade. The C4 HD caliper and the 1LE caliper are the same. Figures huh?

Ed

Which brake hoses are you going to use with the HDC4s? And what is the min clearance between the top of the caliper and the rim?

I just looked up on Autozone rotors for
BRAKE ROTOR - FRONT for a
1992 CHEVROLET CORVETTE ZR-1
WITH J55 BRAKE SYSTEM
LH 55009 $91
RH 55010 $90
for the regular AIMCO rotors. Are the rotor's cooling veins directional from GM?

Hoses can be just standard rubber hoses, or upgrade to Earl's front lines. There's right at 1/2" from the top of the fins to the inside of the rim...plenty of room. I have a closer pic of it but I didn't post it...I will tonight.


Ed

I was doing some research today and GM and the parts stores all list different p/ns between the 1LE and the C4 HD calipers. I don't have a C4 caliper for comparision, but from the pics you posted it looks like they are different. The 1LE brake hose connects to the side of the caliper and the C4 looks like the hose connects to the back of the caliper. Could you confirm this difference? The C4s at autozone are $88 each + core when the 1LEs are $34 + core, so there is a big price difference.

If the 1LEs are dimentionally the same and fit the C4 carrier, then that may be a cheaper route, but may require a longer brake hose.

As side note, Napa has the 13" rotors for $59 each (buck cheaper then the 12" rotors they sell )

I've been wrong before, so I'll do more research on the calipers.

I got the 1LE hub done today. I will post pics later as I'm leaving now. Anyhoo, the face of the 1LE hub sits .318" higher than a standard hub face does. Also, the 1LE hub face is a whole lot thicker than the standard rotor so there's gonna be less of the possibility of cracking the hubs with these. So let's do some math here:

My setup: 13" rotor, standard hub, .250" bracket, and a .125" spacer to get the bracket in there. So if you add all that up, you get a total of .375" (3/8") "overall bracket thickness"

"New setup": With the 1LE hub which moves the rotor out .318" more than the standard one, you can do away with the .125" spacer and add that to the .250" bracket, so you get, again, .375" (3/8"). Then subtract .318" from that and you get .057, which shouldn't be an issue. We'll see what happens when I put it together.

I'll let you know, pics later.


Ed

OK, here's the side by side of the 1LE and standard rotor hubs, 1LE on the left. Note the differences in height, hub face thickness, and distance from the top of the bench to the back of the hub face.

Here's the difference in face height, taken with a depth mic. I got ~ .317-.318".

That’s sweet news Ed. I really like how the 1LE rotor uses the bigger bearings like the caprices use and how the hub is thicker, more piece of mind for me.

As for the caliper mounting bracket the difference between the stock rotor hub and the 1LE rotor hub is about 5/16 and the thickness of the caliper mounting bracket with a stock rotor hub is 1/4. So 5/16 + 1/4 = 9/16; that would be a very thick and very heavy bracket. Do you have any ideas on how to we could make the bracket thinner with a 1LE hub?

Another idea for the caliper mounting bracket is to use a 3/8 bracket and weld on 3/16 spacers. Baer uses the spacer method and on the 4'th gens shown below.

Yep, spacers like those will work fine, and I'll do that if I have to. Making them would be no problem.

Ed

Ed, I see that there is a .318" difference in the height of the face when comparing the two hubs, but when they are installed on the spindle is that difference still there? So if the 1LE rotors are fitted to a car, the wheels will stick out .319" farther then the stock 10.5" rotors??

Has it been confirmed that the Caprice rotors use the same size bearings as the 1LE rotors?? If so wouldn't it be viable to use the Caprice rotors as a hub as well. May be a cheaper alternative.

Tom

Yep...the difference is still there. Confirmed when I made up my custom Wilwood front setup. Used cutdown 1LE hubs to make hubs. I also had a cutdown 10.5" rotor hub to compare with. Wheel will be spaced .319" farther outwards when mounted on spindle. Inside bearing reference point on both 1LE and 10.5" rotors is exactly the same.


Had some race wheels that used to rub against steering arm when mounted on 10.5" rotors. Required 1" of spacers to clear. Changing to Wilwood setup enabled me to run with only a single 1\4" sapcer. Wilwood hub face took up .500"....1LE rotor hub took up another .250"+ . Leaving the difference of only 1\4" or so.

I agree. The inner bearing location is the same on both rotors/hubs but the rest is different. Using Caprice rotors has been brought up before but IIRC the stud pattern is different and would require new stud holes to be drilled and to me it's not worth it.

Thanks Chickenman for a great explanation.

Luke: That pic was from a 4th gen C5 conversion kit, right? I think I saw it before but I can't remember where.

Ed

OK...I got the HDs fitted up tonight. They fit great with a 1/2" thick overall bracket. Rotor is centered very well and I'll have pics up hopefully tomorrow.

Now, I used a 3/8" bracket (same as the regular C4s) and put a 1/8" thick washer between the carrier and the bracket. You could just go ahead and make a 1/2" thick bracket but I think that's overkill, plus it would be a beetooch to cut 1/2" steel they way I make brackets so I'll stick with the 3/8" stuff. I'll be running these on my RS soon.


Ed

Ok, here we go....First is a pic of the 1LE hub with new studs and the C4 bracket on the spindle. Most of the stuff is the same as the standard C4 kit.

Now here's the difference that makes the HDs work. You need an additional 1/8" clearance so I added 1/8" washers to the bracket. You could use a 1/2" thick bracket but I didn't want to make more when I already have brackets that work.

Next install the rotor and carrier and bolt it up as usual:

Hd caliper, pads, and retaining pin. How's that?? These will be on my car by the weekend and I'll give a report.

Ed

Wow! If I understand this correctly.....you're telling me that since I already have 1LE brakes, I can machine my rotors into hubs and, buy ZR1 cradles and rotors, and fabricate a new mount bracket and I have 13" ZR1 front brakes. My 1LE calipers, lines, and pads are reused......right?

From the pics, it looks like the caliper is rotated further down then the 1LE setup so I don't think the brake hose will be long enough to reach. The 1LE hose bolts to the side of the caliper and the C4 to the back. I too would like to reuse as much 1LE stuff as possible, esp since the C4 calipers cost alot more then 1LEs. Maybe the hose bracket on the strut could be relocated to allow sufficient reach for the 1LE calipers.

Ed, I tried to PM you but your box is full.

Also, is there any true advantage to the 13" C4 caliper vs. the 1LE caliper? From what I can tell, the attachment point for the brake line is the only differentce.

I'm 99% sure the 1LE caliper and the HD caliper are the same, they look identical to the 1LEs on my Iroc.

Justin, that's a passenger caliper on a driver's side spindle...or vice versa, so the pic isn't truly showing how it would be located on the car. Again, I used the same C4 bracket as the Standard C4s use so it's located in the same spot. Also, the C4 and 1LE calipers have the brake line bolt holes in the same locations (on the side) so I don't know where the confusion is regarding the brake line, they bolt on the same and use the same banjo bolts. Drain, I think you're right on your idea. You can reuse what you have and get the carriers, hubs, and bracket and go. I rebuilt the HDs and fully compressed the pistons into the bores and slid them over the HD rotors (1.1" thick). There's a lot of play in them so I'm sure they are also sized to fit over the slightly thicker 1LE rotors.

PS: I cleaned out my mailboxes...


Ed

Thanks Ed!

What caliper carriers are you using. I look on autozone and couldn't find them for the ZR-1 brakes.

Thanks
Joey

Ed,
There is a difference between brake hose mounting location on the 1LE vs C4 HD calipers; take a look at the pics below. Also the C4 HD calipers have different part #’s then the 1LE calipers.

For more pics of the C4 calipers go here
For another pic of the back of the 1LE caliper go here

Here is a pic of a right front C4 HD caliper

Here is a pic of a right front 1LE caliper

Here are the GM part numbers you need: 10181207 & 10181208 They are $33 each from gmpartsdirect.com

Here's the pic with part numbers:
Note: the caliper part numbers in this pic are for GS calipers if you want the standard 13 inch HD calipers the part numbers are 12520231 & 12520232

I must say, Luke, you know some schizznit....I have NEVER seen the caliper you listed as the 1LE...never. I am running Fenco "1LE" remanufactured calipers from Auto Zone on my Iroc and they are exactly like the C4 HD calipers in my shop and those you posted as C4s. Guess they'll work on a "1LE" car, huh??

But anyway, there's still no difference, IMO, in the calipers themselves. They will bolt on the same, have the same piston bores, and use the same pads. I like the hose coming off the back side anyway, you'd have to use a fairly longer hose with the other caliper.

Ed

Other then the hose mounting position they appear to be the exact same casting, I see no reason you could not interchange them. What I can’t figure out is why GM bothered moving the hose to the side on the 1LE calipers when they could have saved money and just used the C4 HD caliper unless the C4 HD caliper was designed after the 1LE caliper.

Is there any clearance issues with the hose mounted on the back of the caliper on the HD’s?

EDIT: Baer’s calipers (basically remarked GS calipers) also have the hose exit of the rear of the caliper; I guess it really doesn’t matter what so ever.

My 1LE fenco calipers from autozone look just like the 1LE ones 89 Iroc Z posted.

I can also attest that my 1LE calipers from autozone also look like the ones 89 Iroc Z posted.


Tom

I'm an idiot. I didn't look closely enough at it last week I guess. Here's my front caliper on my Iroc:

ed,
Your 1LE caliper is the same way.....
http://f1.pg.photos.yahoo.com/ph/tar...e+caliper..jpg
and
http://f1.pg.photos.yahoo.com/ph/tar...installed..jpg

Try again..Man do I feel like a jackass...

Man this post is scrolling like a chat room . Well it's good we got that all cleared up. Ed, let us know how the C4 HD's turn on the car, I really can't decide between HD and LS1's now.

The 1LE caliper is alot cheaper then the Vette so if the hose will reach, that would be a much cheaper solution. Plus it would save having to buy calipers over again for 1LE people upgrading. Thats why I kept bringing up the subject of hoses and how they attach.

On advanceautoparts.com the 1LE caliper is $4 cheaper then the C4 HD caliper. So I would just buy the HD caliper